Directional couplers are passive radio frequency components used in radio frequency and microwave signal routing for isolating, separating or combining signals. With advances in telecommunications and wireless technologies, directional couplers are required to support wide bandwidth, have high directivity, better coupling and provide better isolation. Micro strip based directional couplers have proven to be compact with ease to integrate and hence popular.
However, in most directional couplers, there is a trade-off between bandwidth, directivity and compactness. This trade off works satisfactorily in case of narrow band or for extremely high frequencies and provides high directivity along with compactness.